From 644c50021575294ac586663792c7fb0024e9ad8b Mon Sep 17 00:00:00 2001
From: Jordan Rinder <rindjord@umich.edu>
Date: Sat, 8 Oct 2022 16:39:23 -0400
Subject: [PATCH 1/3] Add Catalan number to maths

---
 DIRECTORY.md            |  1 +
 maths/catalan_number.py | 51 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)
 create mode 100644 maths/catalan_number.py

diff --git a/DIRECTORY.md b/DIRECTORY.md
index 64e9d5333a2f..c3fded227cb7 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -475,6 +475,7 @@
   * [Binomial Coefficient](maths/binomial_coefficient.py)
   * [Binomial Distribution](maths/binomial_distribution.py)
   * [Bisection](maths/bisection.py)
+  * [Catalan Number](maths/catalan_number.py) 
   * [Ceil](maths/ceil.py)
   * [Check Polygon](maths/check_polygon.py)
   * [Chudnovsky Algorithm](maths/chudnovsky_algorithm.py)
diff --git a/maths/catalan_number.py b/maths/catalan_number.py
new file mode 100644
index 000000000000..3267ad966f33
--- /dev/null
+++ b/maths/catalan_number.py
@@ -0,0 +1,51 @@
+"""
+
+Calculate the nth Catalan number
+
+Source:
+    https://en.wikipedia.org/wiki/Catalan_number
+
+"""
+
+
+def catalan(number: int) -> int:
+    """
+    :param number: nth catalan number to calculate
+    :return: the nth catalan number
+    Note: A catalan number is only defined for positive integers
+
+    >>> catalan(5)
+    14
+    >>> catalan(0)
+    Traceback (most recent call last):
+    ...
+    ValueError: Input value of [number=0] must be > 0
+    >>> catalan(-1)
+    Traceback (most recent call last):
+    ...
+    ValueError: Input value of [number=-1] must be > 0
+    >>> catalan(5.0)
+    Traceback (most recent call last):
+    ...
+    TypeError: Input value of [number=5.0] must be an integer
+    """
+
+    if not isinstance(number, int):
+        raise TypeError(f"Input value of [number={number}] must be an integer")
+
+    if number < 1:
+        raise ValueError(f"Input value of [number={number}] must be > 0")
+
+    current_number = 1
+
+    for i in range(1, number):
+        current_number *= (4 * i - 2)
+        current_number //= (i + 1)
+
+    return current_number
+
+
+if __name__ == '__main__':
+    import doctest
+
+    doctest.testmod()

From fe88a0b17db68e6b4d83237591d34786243f9623 Mon Sep 17 00:00:00 2001
From: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Date: Sat, 8 Oct 2022 20:41:15 +0000
Subject: [PATCH 2/3] updating DIRECTORY.md

---
 DIRECTORY.md | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/DIRECTORY.md b/DIRECTORY.md
index c3fded227cb7..668da4761f74 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -475,7 +475,7 @@
   * [Binomial Coefficient](maths/binomial_coefficient.py)
   * [Binomial Distribution](maths/binomial_distribution.py)
   * [Bisection](maths/bisection.py)
-  * [Catalan Number](maths/catalan_number.py) 
+  * [Catalan Number](maths/catalan_number.py)
   * [Ceil](maths/ceil.py)
   * [Check Polygon](maths/check_polygon.py)
   * [Chudnovsky Algorithm](maths/chudnovsky_algorithm.py)
@@ -633,8 +633,9 @@
 
 ## Physics
   * [Horizontal Projectile Motion](physics/horizontal_projectile_motion.py)
-  * [Lorenz Transformation Four Vector](physics/lorenz_transformation_four_vector.py)
+  * [Lorentz Transformation Four Vector](physics/lorentz_transformation_four_vector.py)
   * [N Body Simulation](physics/n_body_simulation.py)
+  * [Newtons Law Of Gravitation](physics/newtons_law_of_gravitation.py)
   * [Newtons Second Law Of Motion](physics/newtons_second_law_of_motion.py)
 
 ## Project Euler

From 1807be197155dec0008d4436f5cc0d8ef8c37780 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 8 Oct 2022 20:43:44 +0000
Subject: [PATCH 3/3] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 maths/catalan_number.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/maths/catalan_number.py b/maths/catalan_number.py
index 3267ad966f33..4a1280a45bf2 100644
--- a/maths/catalan_number.py
+++ b/maths/catalan_number.py
@@ -39,13 +39,13 @@ def catalan(number: int) -> int:
     current_number = 1
 
     for i in range(1, number):
-        current_number *= (4 * i - 2)
-        current_number //= (i + 1)
+        current_number *= 4 * i - 2
+        current_number //= i + 1
 
     return current_number
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     import doctest
 
     doctest.testmod()